Method of making electric coils.



J. L. MILTON.

METHOD OF MAKING ELEGTRIG cons. APPLIOAIIOH FILED NOV.12, 1910 RENEWEDDOT. 4, 1912. I 1,046,21 1 Patented Dec. 3, 1912.

3 SHEETS-SHEET l.

Z7 Z6 26f J. L. MILTON.

METHOD OF MAKING ELECTRIC COILSQ (APPLICATION FILED NOV. 12. 1910. RENEWED 001'. 4. 1912- 1,046,21 1. Patented Dec.3,1912.

3 SHEBTS-SHEBT 2.

J. L. MILTON.

METHOD OF: MAKING ELECTRIC COILS. APPLICATION FILED nor-12, 1910 RENEWED OUT. 4, 1912.

3 SHEETS-SHEET 3. i

Patented Dec. 3, 1912.

' To all'whopt it may concern Joni: nwxs mu t, on enrolled, "mm-1101 mn'rnon or Maxine nnnctrnlo coins;

l Specification of Letters Yatent. Pafented Dec, 3, 1912.:

Application iiled Hovembe'r 12, 1310,,Seria11i o. 591,929. Renewed Ootober, 1912, Serial- No. 723,98.

Be it known that 1, JOHN L. Minion, a-

citizen. of "the United States, residingat cylinder 1 engine.

Chicago,-in the county of Cook and State" of Illinois, have invented a certain new and useful Imp-rovementin Methods of Making Electric Coils, of which the following is a full, clear, concise, and exact description,

reference being had to the accompanying drawings -torming a" part of this specification.

of for-iniiig them.

lt was my aim 1n Connection with the de-- velopment of a high-tension ignition systemior nternal combustidn engines, and

particularly those used? on automobiles, to

make an induction-coil of theTesla type,-'

that is, a-co'il having *a secondary winding ohwire' over which is wound a primary winding of coarser wire and in which there is no 'iron core.

It. was my objectjto'idevelop a coil of this general ty'pefwhich might be attached directly to each of; the spark plugs of a multi- This meant necessarily that the'coilfwould be subjected to a big temperature,- due.

to its proximity to the cylinder of the engine. I It would also be subjected to'joil and grease and generally to very'severe conditions ofuse.

' Ordinarily,

coils used in ignition work are impregnated with wax to establish and maintain the very necessary. Subjected to the. use towhich I proposed td put my coils, however, the wax wonl-d soon melt and the coil wouldbe dc I 'stroyed- I decided, thereforefifdpossible,

to make a coil in'which the several layers at wire and the several conductors of each layer would be insulated fromone another 1 by rubber which would 'withstandthe high rubber proved that the --easily accomplished.

deg 'cc; of which the coil, would be subjected; tempts to build coils thus insulated. with result was not at all It apparently would be necessary to' use order to gain the necessary strength and rigidity in the completed coil; In order-that vulcanize rubber in and around the copper wire, which was a practical necessity, I found that the copper was attacked'chemically by "the sulfur, thus seriously:

invention relates to high-tension elec 'tricaljc'oi-ls and particularly to th process.

should be completely filled high degree of insulation heat. and-"the oil and grease 10' A vulcanized rubber in impairing the conduct-ivlty of the wire. fur and copper, furthermore, formed a conductive path which was readily traversed The compound of S1117"- by the high-tension currents, with the result that the coils thus made proved useless for r the intended purpose. Another thing which I discovered in quired coil was that-the silk insulation which would ordinarily be provided upon the fine.

wire intended for the secondary winding my efforts to make the rewould not withstand the high temperature necessary to vulcanize the rubber. Another 1 difficulty was encountered in' attempting to vulcanize the coils,

due to the chemical action of; thesulfur upon :the iron molds used for vul'canizing purposes The suliids thus 'formedw'ould strike into the coiland destroy the insulation and in addition make the finished coil very dirty, Altogether the problem became a very process herein described that it'becamepos "sible to construct the coil which Ihadset ws iny goal.

It was my aim between the conductors of the finished with rubber. found that if any air pockets were left between the several condli'ctors in the finished coil,.- these would form easy paths for the high-tension current and it became neces- 'sary, therefore, to avoid entirely the inclusion of any such pockets within the mass of the completed coil.

Without recounting the various steps and processes which I made before success had been attained, I shall proceed atoms to a description of the process which finally eventuated and which has re-..

sulted in the production of coil-sgivin'gthe 'most complete satisfaction in service.

' Generally stated, the process of my invention consists in the winding of successive layers of -w1re,othere being wound between each' successive layer or" wire a layer of ,1

I devised espeduplex rubber gum which cially for the purpose. I shall refer more particularly to this rubber material thus laid between the layers of wire. Sufiice .it

now to say that these alternate layers of rubber gum and wire arelaid up until the necessarynumber of layers have been wound.

The rubber'w hich' is laid between the successive layers of wire is preferably quite 'diflicult one, audit --was only after a long series of trials and experiments'end after the invention of the that all of the interstices coil many trials --of ber flanges of .special composition. I

adhere 'to the. tacky rubber which is ex posed atthe' end of each layer. Terminals,

tacky and very soft and pliable. 1 The necessity for extreme pliability resides in the fact that the wireis Wound. under some tension' with thepurpose of compressing the layer of rubber which has been laid over the next lower coil in such a way as to force the rubber into the grooves between thelower layer of wire. Not only is the rubber forced into the grooves between the wires of the layer beneath that which is ,beingwound, but the rubberis also crowded up into the grooves between the, layer which is beingwound, the rubber bein thus made in a large-measure to fill the interstices between the conductors of a given layer of wire and between the conductors of one layer and the next succeeding layer.

I Without describing now certain details which are important in connection with these steps of the process, I may state that when the, several layers of wire have beenlaid in this wayypreferably between the flanges of a rigid spool, the supporting 'fianges are removed and replaced with {lub- T ese aving preferably been attached to the ends of the coils, the whole is clamped very J tightly in a vulcanizing mold of tin or aluminum and heatedto the req'uiredtemperature. 'This vulcanizing process tends to expand therubber to a certain extentand the interstices between the conductors are aim-1S completely fil w rubber thermore, therubberflanges become firmly attached to, or erhaps rather made a part ,of, the rubber w ich fills the spaces between the conductors. I

Therubber which I use is a special combination, comprising alternate layers of compounded rubber containing a considerable percentage of sulfur and of pure rubber um Such as Para gum. The Para gum is rdlled 5 into a very thin sheet and-is applied to the compounded rubber sheet before .the duplex rubber tapethus formed is wound intothe coil. The sheets of Para gum which I use p for this purpose are known in the rubber trade asgutta-percha tissue. I have found that the duplexrubber above described does I not attac the coppe wire as would the rubber or inarily em loyed for vulcanizing purposes. Furthermore, I employ a copper wire which is thoroughly well tinned toafford. protection against the attack of the sulfur contained in the rubber.

ther preventive a ainstthe chemical combi nation'of the 'su fur in the copper of the 60. wire I employ a lower temperature for vulcani-zation than is ordinarily employed,the

-periodduring which the vulcanizing process is carried on being extended, if neoessa ,4

inorder. that the rubbermay be efl'ectual y I 5 cured I shall describe .this' and the vari As a fur-' already coated with the P2 rubber mixed with a. greater or'l ous details of the process of my invention in 1 tion of. the hub and spool and arbor upon which-the coil is wound; Fig. 4: is a crosssectional view of the hub, taken near one end to show the method of connecting one end of the secondary coil with its terminal; Figs.- 5, 6 and 7 showvarious phases of the opera-- tion of winding the secondary coil, the views being partial cross-sections very much enlarged; Fig. 8 is a cross-sectional view showsame; Fig. 3 1s a view largely in cross-secing the laying of the primary winding; Fig.

9 1s a cross-sectional view showing the method of attaching a terminal to the primary winding; Fig. 10 is another View in plan of the terminal, showing the method of attaching it to the coil; Fig. 11 shows the method of affixing the rubber flanges to the front and back of the wire-wound section of the coil; Fig. 12 shows in cross-section a strip of the rubber tape with its fabric back ing which is used between the successive 1 layers of. wire; Fig..13 is a cross-sectional view of the duplex rubber tape slightly separated from its backing; Fig. 14 shows the manner of Winding the tape upon the hub or core; and 'Fig'. 15 shows -in cross-sectionthedmold containing the coil to be vul can-. 1ze

Like reference characters ,are applied to the same parts throughout the various figures.

Now, to describe the'process in detail and i in the best manner in which it may be carried out so far/as I am aware, I shall refer first to Fig..- 3, which shows a hub 20 of vulcanized fiber, there being a series of sinall grooves 21, 21 turned on theperiphcry. of this hub to make more firm the grip.

of the rubber which, is to be laid thereon.

Near one end of this .hub the small holes 22, 22 are drilled to receive the U-shaped wire 23. A saw-slit at 24 serves to receive rubber tape; A 'piece of this material is shown in cross-section in Fig.z12,' together with its fabric backing 25 This backing It may be purchased in the is called compounded rubber-{gum i a gum containing, as I under stand it,

of cheaper and less tenacious tains also-moreg r less sulfuri I v One importafit'fs'tep of the invention 1s to [is of cotton or any firm tapelike material.-

rket

ss 'eontent 55. laying the wire is begun,

dled and put in place,

I This produces a stick tightly operator to winda layer of the rubber sheet lay a layer of rubber between each layerl of wire. "If, however, this Weak compounded rubber be made strong enough to be hanit must be so thick that. it will give the finished coil too great bulk, and will also make an inefficient coil. In order, therefore, to secure a thin rubber tape having the requisite strength, I com-- bine the sheet of compounded rubber with a layer of pure Para gum rolled to a thickness'of but'a few thousandths of an inch. This sheet rubber may be purchased in the market, where it is known as gutta-percha tissue. The layer of compounded rubber is shown at 26 and the layer of pure Para rubber at 27, the latter being wholly uncured and containing no sulfur whatever. The compounded rubber is very sticky and the layer of Para gum adheres firmly to it. rubber tape mounted upon a fabric backing, the fabric side of the rubber bein very stickypr'tacky and the other side of pure Para rubber. The two layers of rubber adhere to each other as one and both to the fabric backing. The duplex rubber sheet having been prepared in this way, the rubber sheet together with the fabricb'acle' ing is cut into strips of a width; slightly greater than the distance bet-ween the metal flanges .28, 28 of the winding spool. The flanges flanges 28, thereby causing grooves between'the wires, as

layer of wire having been clamped to the hubby .p

the arbor' 29 and this arbor having been mounted in a winding machine or lathe, an end of the duplex rubber sheet is separated from the fabric backing at 30, as shown in Fig. 13, and the end of the rubber is pressed firmly upon the hub- 20. The rubber will to the hub, thus enabling the about the hub while he fabric is pulled away from the rubber, asbest illustrated in Fi 14. k

vhe'n a layer of, rubber has been wound about the hub,.-the strip is cut off and the free end stuck down upon the circlet which has been wound about the hub. The connector 23 having been previously inserted through the holes of the hub, the'rubber layer is cut away slightly just over this connector in order that'the inner end of the fine secondary wire may be slipped under the connector and, 'f desired, the wiremay be soldered thereto. Ndw ,the process of the niandrel and and the wire being to' occupy the space at the turn of: the layer acts inv like manner, so I spaces'at both heads of 7 The grooves betweenthe turns of a layer.

spool being rotate wound in a continuous layer across the spool spool comprising the 28 and the hub 20 upon' from left to right. The copper wire 31 shown in several of the figures is, as previously stated, well tinned and preferably with an in ulation of cotton 31. Fig 5 shows in cross-section a part of the tinned winding flanges which the layer of duplex rubber has been laid. For convenience, in. the figures other than 12, 13 and 14 strip tobe turned as'shown in Fig. 6, the-tension ofthe-wire,

will not only force the rubber up into the v shown at 33,. 33, but so also that when the wire 34:.at' the end of the layer is laid it will find sufficient rubber to fill the space at the end of the layer and to leave a good facing of rubberto which later the rubber flange may tachedQ Fig. 6 is intended to show the first layer of'the secondary'coil in place except for the last turn which is just in the process of being brought down. The tension of the wire in winding should be regulated or adjusted so that .the successive turns will thoroughlye mbed themselves 1n the rubber, as shown in Fig. 6. Fig.'7 shows the first already in place.- It shows also the second'layer of wire in place except for the final turn 35 which is in the being laid. A second layer of duplex rubber tape 26- is laid over the first layer of wire just as the'first layer of rubber was laid over the hub. Although duplex rubber tape which is used for this purpose does not have sufiicient strength to permit of its being wound the rubber between the grooves of the layer of wire already in place, the rubber is 'so plastic that the winding of the successive layer of wire will not only between the grooves of the layer being wound, but also between the grooves of the as indicated in Fig.

layer already in place, I 7. Here again the layer of rubber is cut/a little wider than the.distance as indicated in Fig. 7 last turn of a layerforce Not only .-does the the rubber fully end, but the first that the rubber is forced out to fill thethe coil.

under. tension to force force the rubber the first layer of rub- 20- in 'similar'manner. I

be at- 2 between the spool heads in order that the last turn may into the space at 36,

layers of wire have been-laid, the 'outer -I layer is covered with one or 'more layers of the duplex rubber tape. The primary winding' of coarser wire is then wound in the same manner as were the several layers of the secondary winding. In the coils which I'have made in accordance with this process a single layer of primary wire has been. sufficient and such asingle layer is shown in,

thedrawings. For convenience in dwinding,

- I have provided a hole in the metal flange theend of the wireiwhich 28, as indicatedfin dotted lines at 37 in Fig. 8, and into this hole in the flange I insert is to form "the primary" layer. f The wire is then wound across the spool just as were theseveral layers of secondary wire, the rubber tape 26 being forced up into the grooves due to .wound. In this connection the tension of the primary wire while being I may say that since the rubber-must be forced 'a greater distance into thegrooves of the larger. wire, I find it desirable to wind the heavier wire- 7 under a correspondingly increased tension.

When this coarser primary windinghas beenlaid, and one, or more layers of rubber wound upon it, I remove the end of the wire "which was inserted in the hole in the spool head and slip it throughthe eye 38 of the terminal clip 39. The wire is preferably soldered within this eye to make a' surev and permanent connection.

The style of the terminal is best illustrated in-Fig. 10. Itcomprises the clip 39' into. which the groove head l0 is'friveted, as shown in Fig. 9. Aseries of holes 41, 41 provide openings through which the. rubber is pressed in vulcanization, the rubber studs thus formed giving aid .in holding the terand the heads of substantiallydiametrically opposite in the '45 Ininal clip place. A linen thread 42. is

coils which-I have constructed. When the terminals are thus inplace and. the whole coil; bound around with the rubber tape', the

partiallycompleted coil is removedfrom the v windingspool shown in Fig. 3 and the rub .50 i .11; F ig. .11.. These heads are of washer is provided with a hole ters with the hole through the hub onwhich 55 ber heads 44, t' l'are applied as illustrated compounded rubbers. For convenience, each diskv or.

which registhe coil is wound. In view of the sticky,

tacky nature of the rubber tape which-has.

been wound between the layers of wire and whichhas been'forced out at the end of each layer, the disks of compounded rubber adhere'strongly to the ends of the coil. The

' whole coilis then placed'in the tin or aluminum mold shown in Fig. 15. The halves of the mold 45 and 461 are closed by means of the screws 47, 47. The plunger 48 ,is then pressed smartly against the wh'o'le'coil by means-ofthe clamp screws 49,49 The capillary-holes 50, 50 allow the escape of any air which may have been retained.' The mold containing the coil is then placed in a vulcanizing oven or otherwise subjected to a vulcaniz ing temperature which,-in the case of the-gums which I have employed, is about 340 degreesFahr. I-have found thatwhen this temperature was maintainedfor a period of" about six hours, the vulcanization was complete or at least such as to give most excellent results in the finished coil. This temperature is nothigh enough to destroy the cotton insulation which in a coil of this kind I have found, therefore, to be much .,'preferable to the'silk' insulation which ordization, furthermore, rubber and. generally so that the resultis practically a tinned cop per wire thoroughly embedded in a 'mass'of tends. to expand the fur of which has the wire, coil for. tion.

not attacked the copper of there results an extremely eflicient hlgh-tension electrical transformacements or fuses the rubber heads to the several cylindrical layers of rubberwhich intervene between the-layers ofwire. There are, therefore, no air spaces either in the -body of the coil or ;-at the ends where the heads are vulcanized into homogeneity with the layers of rubber which intervene between. the turns of wire; process is a coil also of very attractive ap-' pearance and of very small size as measured by its electricalfioutput.

front View ofthelfinished'coil. In Fig. 2 is nar'ily would be used upon the Wire of .the' secondary winding. The process of vulcanito cement it together ers are completely filled with rubber the sul The result of my Fig. 1 shows a" vulcanized rubber. In other words, the int erstices between the wire forming the coil The process of vulcanization thoroughly shown a sideelevation in which may be seen the terminal which is connected with the inner end of'the secondary winding. This terminal consists of the machine screw 51 which is held being. an L-shaped clip 53 which is clamped under thehead of the screw 51. It will be .remembered that a connector 23 was run through the hub from the inner end of the secondary winding,- tension current which this winding, the electrical contact between the connector 23' and the screw 51 will ordinarily bev suflicient without solder or other special device. L.

I realize that I have explained the several steps of this process inconsiderable detail, for the reason that I encountered unsuspected difiiculties at almost every point-Yin 1-15 in place by'the-nu t 52, there and as it is a highis delivered from my attempt to produce the result required. I have thought best, therefore, to plicit in my description of the process, but do not for this reason wish to be limited to non-essential details.

The scope of my invention is indicated only by the appended claims in which I state the invention which I desire to secure by Letters Patent:

1. The process which. consists in alternately winding a layer of rubber tape comprising a layer of compounded rubber and a layer of guttapercha tissue and then winding a layer of cotton covered tinned copper wire, placing compounded rubber heads upon the ends of the coil thus formed and then vulcanizing the whole.

2. The process which consists in winding alternate layers of rubber and tinned copper wire, each layer of rubber comprising in turn a thickness of compounded rubber containing more or less sulfur and a thick ness of pure Para gum, the wire being wound under tension in order that the rubber may be forced into the grooves between the successive turns of wire, and then vulcanizing the whole under pressure.

be ex-- consists in winding 3. The process which tinned copper wire,

a layer of cotton covered then winding a layer of duplex rubber tape over the layer of wire, then winding another layer of wire under tension in order to force the rubber into the grooves between successive turns of wire, then winding anv other layer of rubber and so on indefinitely lthe layers of rubber being formed of a thickness of compounded rubber containing more or less sulfur mounted upon a thin llayer of guttapercha' tissue, the tapes of rubber being cut slightly wider than the space to be occupied by the layers of wire when wound, applying compounded rubber heads to the ends of the coil, compressing the coil thus formed in a suitable mold and then vulcanizi-ng the coil substantially as described.

In witness whereof, I hereunto subscribe my name this 22d day of August, A. DJ 1910.

JoHN LEWIS MILTON.

Witnesses:

ALBERT C. BELL, LEONARD E. BOGUE. 

